The present invention pertains to a coupling for a breathing tube system with an inner tube and an outer tube.
A coupling for a breathing tube system, comprising an outer tube with an inner tube enveloped by the outer tube, has become known from EP 150 912. A first connection part of the coupling has a first connection piece, which is connected to the outer tube, and a connection for the inner tube, which is arranged eccentrically on the first connection piece, is located within the first connection piece. The second connection piece of the coupling is provided with an inner cone and is used for connection to a patient tube or a gas mask. The patient receives the fresh breathing gas from the inner tube and breathes the exhaled gas back into the outer tube. The breathing gases are mixed in the area of the second connection part, because there is no separation between the different types of gas. In addition, the fresh breathing gas flowing in via the inner tube flows off unused into the outer tube during the phase of exhalation.
The primary object of the present invention is to improve a coupling of this type such that the breathing gas being delivered by the breathing tube system can be fed to the user over paths that are separated from one another in terms of flow.
According to the invention, a coupling between a breathing tube system is provided with an inner tube and an outer tube. A first connection part is provided with a first connection piece for the outer tube and with a first connection for the inner tube. The first connection is arranged eccentrically in the first connection piece. A second connection part is provided with a second connection piece, which is in flow connection with the first connection piece. The second connection part provides a second connection, which is arranged concentrically in the second connection piece and which is connected to the first connection in terms of flow.
A measuring connection, which opens into a flow channel surrounded by the connections, may be present in the connection area between the first connection and the second connection.
The length of the first connection may be selected to be such that it projects beyond the first connection piece. The length of the second connection may be selected to be such that it projects beyond the second connection piece. The first connection piece may be provided with a first undercut for fixing the outer tube. The second connection piece may have a second undercut.
It is especially advantageous to provide a measuring connection, which opens from the outside into the flow channel surrounded by the connection, between the inner connections of the coupling. For example, a temperature-measuring sensor, with which the temperature of the gas flow flowing through the connections can be measured, may be inserted into the measuring connection. As an alternative to the temperature measurement, the measuring connection may also be used for breathing gas analysis with an exhausting gas analyzer.
For the case of temperature measurement on the coupling, it is advantageous to design the flow channel as a measuring chamber with an enlarged cross-sectional area compared with the internal diameter of the connections in the area of the measuring connection. Smoothing of the flow in the area of the measuring connection is thus achieved. The enlargement of the cross section is obtained by the measuring chamber being arranged in the overlapping area of the eccentrically fastened first connection with the concentric second connection. The cross-sectional areas add up in the overlapping area due to the radial offset of the connections.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawing and descriptive matter in which a preferred embodiment of the invention is illustrated.